FIGS. 1 and 2 shows a conventional earmuff structure for headset or ear protector. The conventional earmuff structure includes two earmuff shells 1 and 2, battery conducting electrode plates 11 that are directly welded to a circuit board 3 fixed in each of the earmuff shells 1, 2, and two speakers 4, each of which is fitted on a considerably small speaker mounting seat 41 having two hooking heads 42 provided at two lateral sides thereof and foams 40 provided at predetermined positions. The speaker mounting seat 41 is then fixed to two lateral sides of the circuit board 3 via the hooking heads 42 that provide some extents of elasticity, so that the speaker 4 is assembled to the circuit board 3. The above assembling manner has the following disadvantages:    1. The battery conducting electrode plates 11 must be welded to the circuit boards 3 in the earmuff shells 1, 2, and the speakers 4 are assembled to the circuit boards 3 by engaging the hooking heads 42 of the speaker mounting seats 41 with two lateral sides of the circuit boards 3. It is difficult and time-consuming to proceed with the welding and the assembling of the electrode plates 11 and the speakers 4 to the circuit boards 3.    2. The earmuff shells 1, 2 have quite small interior space, and the battery conducting electrode plates 11 welded to the circuit boards 3 are very close to two sides of the earmuff shells 1, 2. It would be very inconvenient to change batteries 5 in the small space of the earmuff shells 1, 2.    3. The speakers 4 are assembled to the circuit boards 3 by very tightly engaging the hooking heads 42 of the speaker mounting seats 41 with two lateral sides of the circuit boards 3. It is uneasy to disengage the speaker mounting seats 41 from the circuit boards 3 when the speakers 4 are failed and require replacement.    4. The speakers 4 assembled to the circuit boards 3 are located in an open space in the earmuff shells 1, 3. Therefore, the speakers 4 do not output clear and high quality stereo sounds.